synthesis and anticancer activity of long-chain...
TRANSCRIPT
Synthesis and Anticancer Activity of Long-Chain Isonicotinic Ester
Ligand-Containing Arene Ruthenium Complexes and Nanoparticles
Georg Suss-Fink • Farooq-Ahmad Khan • Lucienne Juillerat-Jeanneret •
Paul J. Dyson • Anna K. Renfrew
Abstract Arene ruthenium complexes containing long-chain N-ligands
L1 = NC5H4–4-COO–C6H4–4-O–(CH2)9–CH3 or L2 = NC5H4–4-COO–(CH2)10–
O–C6H4–4-COO–C6H4–4-C6H4–4-CN derived from isonicotinic acid, of the type
[(arene)Ru(L)Cl2] (arene = C6H6, L = L1: 1; arene = p-MeC6H4Pri, L = L1: 2;
arene = C6Me6, L = L1: 3; arene = C6H6, L = L2: 4; arene = p-MeC6H4Pri,
L = L2: 5; arene = C6Me6, L = L2: 6) have been synthesized from the corresponding
[(arene)RuCl2]2 precursor with the long-chain N-ligand L in dichloromethane.
Ruthenium nanoparticles stabilized by L1 have been prepared by the solvent-free
reduction of 1 with hydrogen or by reducing [(arene)Ru(H2O)3]SO4 in ethanol in the
presence of L1 with hydrogen. These complexes and nanoparticles show a high
anticancer activity towards human ovarian cell lines, the highest cytotoxicity being
obtained for complex 2 (IC50 = 2 lM for A2780 and 7 lM for A2780cisR).
Keywords Ruthenium nanoparticles �Anticancer drugs �Bioorganometallic chemistry �Isonicotinic ester ligands �Arene ruthenium complexes
This article is dedicated to Professor Malcolm Chisholm on the occasion of his 65th birthday.
G. Suss-Fink (&) � F.-A. Khan
Institut de Chimie, Universite de Neuchatel, 2009 Neuchatel, Switzerland
e-mail: [email protected]
L. Juillerat-Jeanneret
University Institute of Pathology, Centre Hospitalier Universitaire Vaudois (CHUV),
1011 Lausanne, Switzerland
P. J. Dyson � A. K. Renfrew
Institut des Sciences et Ingenierie Chimiques, Ecole Polytechnique Federale de Lausanne (EPFL),
1015 Lausanne, Switzerland
1
Introduction
Arene ruthenium complexes containing chloro ligands are both lipophilic and water-
soluble, which preconditions these organometallics for bio-medical applications such
as anticancer agents [1]. The field of antitumoural and antimetastatic arene ruthenium
complexes has, in recently years, received considerable attention [2, 3], following the
notion of using arene ruthenium compounds as anticancer agents by Tocher et al. in
1992, who observed a cytotoxicity enhancement by coordinating the anticancer agent
metronidazole [1-b-(hydroxyethyl)-2-methyl-5-nitro-imidazole] to a benzene ruthe-
nium dichloro fragment [4]. The prototype arene ruthenium(II) complexes evaluated
for anticancer properties in 2001 were (p-MeC6H4Pri)Ru(P-pta)Cl2 (pta = 1,3,
5-triaza-7-phospha-tricyclo-[3.3.1.1]decane), termed RAPTA-C [5], and [(C6H5Ph)-
Ru(N,N-en)Cl][PF6] (en = 1,2-ethylenediamine) [6].
Isonicotinic acid is widely used for the synthesis of antibiotics and antituber-
culosis preparations [7], and it has strong bactericide effects [8]. We have been
interested in the use of long-chain isonicotinic esters as lipophilic components in
order to increase the anticancer activity of arene ruthenium complexes, while at the
same time, using a molecule that is known to be tolerated in vivo. Only one arene
ruthenium complex containing isonicotinic acid has been reported so far, namely
[(C6H6)Ru(NC5H4COOH)] by Małecki et al. [9], but the biological properties of the
complex were not studied.
In this paper we describe the synthesis and characterization of arene ruthenium
complexes of the type [(arene)Ru(L)Cl2] containing long-chain isonicotinic ester
ligands L and of ruthenium nanoparticles stabilized by these ligands, and in
addition, the cytotoxicity of these agents is reported.
Experimental Section
Synthesis
Solvents were dried using appropriate drying agents and distilled prior to use.
RuCl3�3 H2O (Johnson-Matthey), 1-bromodecane (Sigma-Aldrich), isonicotinoyl
chloride hydrochloride (Sigma-Aldrich), hydroquinone (Sigma-Aldrich) were used
as received. NMR spectra were recorded on a Bruker DRX 400 MHz spectrometer at
400.13 (1H) with SiMe4 as internal references and coupling constants are given in
Hz. Infrared spectra were recorded on Perkin-Elmer FT-IR spectrometer as KBr
pellets. UV–Vis studies were recorded on a UVIKON 930 spectrometer. For the
ruthenium nanoparticles, the particle size was determined using a transmission
electron microscope, Philips CM 200 operating at 200 K, and the chemical
analysis determined by Energy Dispersive X-ray spectroscopy. The compounds
[(C6H6)RuCl2]2 [10], [(p-MeC6H4Pri)RuCl2]2 [11], [(C6Me6)RuCl2]2 [12], [(C6H6)-
Ru(H2O)3]SO4 [13], [(p-MeC6H4Pri)Ru(H2O)3]SO4 [14] and [(C6Me6)Ru(H2O)3]
SO4 [15], 4-(decyloxy)phenyl isonicotinate (L1) [16] and 40-cyanobiphenyl-4-yl-4-
(10-hydroxydecyloxy)benzoate [17] were prepared according to published methods.
2
Preparation of the New Ligand L2
40-Cyanobiphenyl-4-yl 4-(10-hydroxydecyloxy)benzoate (0.1 g, 0.21 mmol) and
triethylamine (0.021 g, 0.21 mmol) were dissolved in CH2Cl2 (100 mL) and
isonicotinoyl chloride hydrochloride (0.09 g, 0.63 mmol) was added. The reaction
mixture was stirred overnight at room temperature. The precipitate formed was
filtered off and discarded and the solution was evaporated to dryness. The yellow
residue obtained was recrystallized several times from ethanol to give a white
product, yield: 0.104 g, 85%. (Found: C, 74.87; H, 6.36; N, 4.76. Calc. for
C36H36N2O5 (M = 576): C, 74.98; H, 6.29; N, 4.86%). IR (KBr, cm-1): 2920(m),
2223(w, mCN), 1723(s, mCOO), 1604(s), 1493(m), 1255(s), 1162(s). 1H NMR
(400 MHz, CDCl3) d ppm 8.89 (d, J = 6.0 Hz, 2H), 8.17 (d, J = 8.8 Hz, 2H), 7.86
(d, J = 6.0 Hz, 2H), 7.75 (d, J = 8.4 Hz, 2H), 7.70 (d, J = 8.4 Hz, 2H), 7.65
(d, J = 8.8 Hz, 2H), 7.34 (d, J = 8.8 Hz, 2H), 6.99 (d, J = 9.2 Hz, 2H), 4.36
(t, J = 6.8 Hz, 2H), 4.05 (t, J = 6.8 Hz, 2H), 1.81 (m, 4H), 1.54–1.32 (m, 12H).
MS (ESI) m/z: 599.3 [M?Na]?. UV–Vis (CH2Cl2): kmax 278 (220124), 228
(56183) nm.
Preparation of the Complexes [(arene)Ru(L)Cl2] (1–6)
A mixture of the appropriate [(arene)RuCl]2 dimer (0.15 g) and two equivalents of
the ligand L1 or L2 in CH2Cl2 solution (25 mL) was stirred for 3 h at room
temperature. The solvent was then removed under reduced pressure, and the residue
was dissolved in EtOH (30 mL). Then the solvent was evaporated to dryness, and
the final product was collected and dried in vacuo.
[(C6H6)Ru(L1)Cl2], 1: yield: 0.363 g,[99%. (Found: C, 55.03; H, 5.83; N, 2.25.
Calc. for C28H35Cl2NO3Ru�0.1 CH2Cl2 (M = 613.5): C, 54.96; H, 5.78; N, 2.28%).
IR (KBr, cm-1): 2925(m), 1747(m, mCOO), 1631(m), 1505(m), 1277(w), 1192(m).1H NMR (400 MHz, CD2Cl2) d ppm 9.31 (d, J = 6.0 Hz, 2H), 8.00 (d, J = 6.0 Hz,
2H), 7.11 (d, J = 8.8 Hz, 2H), 6.92 (d, J = 8.8 Hz, 2H), 5.65 (s, 6H), 3.95 (t, J =
6.6 Hz, 2H), 1.76 (m, 2H), 1.46–1.26 (m, 14H), 0.86 (t, J = 6.8 Hz, 3H). MS (ESI)
m/z: 452.9 [(M-{C6H4O(CH2)9CH3})?Me2CO?Na]?, 391[(M-{C6H4OC10H21})
?H2O?H]?. UV–Vis (CH2Cl2): kmax 337 (4308), 276 (6671), 230 (21465) nm.
[(p-MeC6H4Pri)Ru(L1)Cl2], 2: yield: 0.324 g,[99%. (Found: C, 58.17; H, 6.57;
N, 2.06. Calc. for C32H43Cl2NO3Ru (M = 661.17): C, 58.09; H, 6.55; N, 2.12%). IR
(KBr, cm-1): 2925(m), 1745(m, mCOO), 1631(m), 1505(m), 1250(m), 1187(m). 1H
NMR (400 MHz, CDCl3) d ppm 9.31 (d, J = 6.8 Hz, 2H), 7.98 (d, J = 6.4 Hz,
2H), 7.11 (d, J = 9.2 Hz, 2H), 6.93 (d, J = 9.2 Hz, 2H), 5.49 (d, J = 5.6 Hz, 2H),
5.26 (d, J = 6.0 Hz, 2H), 3.96 (t, J = 6.6 Hz, 2H), 3.05–2.98 (m, 1H), 2.13 (s, 3H),
1.82–1.75 (m, 2H), 1.48–1.28 (m, 18H), 0.87 (t, J = 6.8 Hz, 3H). MS(ESI) m/z:
565.0 [(M-{OC10H21})?Me2CO?H]?. UV–Vis (CH2Cl2): kmax 340 (5135), 275
(6882), 230 (21482) nm.
[(C6Me6)Ru(L1)Cl2], 3: yield: 0.309 g, [99%. (Found: C, 59.02; H, 6.84; N,
1.98. Calc. for C34H47Cl2NO3Ru (M = 689.20): C, 59.21; H, 6.87; N, 2.03%). IR
(KBr, cm-1): 2923(s), 1740(s, mCOO), 1631(w), 1502(s), 1275(m), 1184(s). 1H
NMR (400 MHz, CDCl3) d ppm 9.08 (d, J = 6.4 Hz, 2H), 7.96 (d, J = 6.4 Hz,
3
2H), 7.11 (d, J = 8.8 Hz, 2H), 6.93 (d, J = 9.2 Hz, 2H), 3.96 (t, J = 6.4 Hz, 2H),
2.02 (s, 18H), 1.79 (m, 2H), 1.47–1.27 (m, 14H), 0.88 (t, J = 6.6 Hz, 3H). MS(ESI)
m/z: 620.1 [(M-2Cl)?H]?. UV–Vis (CH2Cl2): kmax 354 (5349), 277 (6368), 230
(18000) nm.
[(C6H6)Ru(L2)Cl2], 4: yield: 0.495 g,[99%. (Found: C, 60.62; H, 5.10; N, 3.29.
Calc. for C42H42Cl2N2O5Ru�0.1 CH2Cl2 (M = 834.55): C, 60.54; H, 5.09; N,
3.35%). IR (KBr, cm-1): 2927(m), 2225(w, mCN), 1725(s, mCOO), 1603(m),
1254(s), 1160(s). 1H NMR (400 MHz, CDCl3) d ppm 9.28 (d, J = 6.4 Hz, 2H),
8.15 (d, J = 9.2 Hz, 2H), 7.85 (d, J = 6.4 Hz, 2H), 7.74 (d, J = 8.4 Hz, 2H), 7.69
(d, J = 8.4 Hz, 2H), 7.64 (d, J = 8.4 Hz, 2H), 7.33 (d, J = 8.4 Hz, 2H), 6.98 (d,
J = 8.8 Hz, 2H), 5.68 (s, 6H), 4.38 (t, J = 6.8 Hz, 2H), 4.06 (t, J = 6.4 Hz, 2H),
1.86–1.74 (m, 4H), 1.50–1.34 (m, 12H). MS (ESI): m/z: 791.1 [(M-Cl]?. UV–Vis
(CH2Cl2): kmax 278 (71012), 229 (28025) nm.
[(p-MeC6H4Pri)Ru(L2)Cl2], 5: yield: 0.432 g,[99%. (Found: C, 62.51; H, 5.80;
N, 3.07. Calc. for C46H50Cl2N2O5Ru (M = 882.21): C, 62.58; H, 5.71; N, 3.17%).
IR (KBr, cm-1): 2927(m), 2227(w, mCN), 1731(s, mCOO), 1606(m), 1261(s),
1168(s). 1H NMR (400 MHz, CDCl3) d ppm 9.23 (d, J = 6.4 Hz, 2H), 8.16 (d, J =
8.8 Hz, 2H), 7.84 (d, J = 6.0 Hz, 2H), 7.74 (d, J = 8.0 Hz, 2H), 7.69 (d,
J = 8.4 Hz, 2H), 7.64 (d, J = 8.4 Hz, 2H), 7.33 (d, J = 8.8 Hz, 2H), 6.99 (d, J =
8.8 Hz, 2H), 5.45 (d, J = 6.0 Hz, 2H), 5.24 (d, J = 6.0 Hz, 2H), 4.37 (t,
J = 6.6 Hz, 2H), 4.06 (t, J = 6.4 Hz, 2H), 3.04–2.95 (m, 1H), 2.10 (s, 3H),
1.85–1.76 (m, 4H), 1.49–1.31 (m, 18H). MS (ESI) m/z: 650.9 [(M-{OC6H4-
COOC6H4C6 H4CN})?Me2CO?Na?H]?. UV–Vis (CH2Cl2): kmax 334 (4558), 279
(47199), 229 (18313) nm.
[(C6Me6)Ru(L2)Cl2], 6: yield: 0.408 g, [ 99%. (Found: C, 61.30; H, 5.87; N,
2.92. Calc. for C48H54Cl2N2O5Ru � 0.5 CH2Cl2 (M = 952.22): C, 61.10; H, 5.81; N,
2.94%). IR (KBr, cm-1): 2924(m), 2226(w, mCN), 1722(s, mCOO), 1602(s), 1260(s),
1166(s). 1H NMR (400 MHz, CDCl3) d ppm 9.01 (d, J = 6.8 Hz, 2H), 8.15 (d,
J = 8.8 Hz, 2H), 7.81 (d, J = 6.4 Hz, 2H), 7.74 (d, J = 8.4 Hz, 2H), 7.69 (d, J =
8.4 Hz, 2H), 7.64 (d, J = 8.4 Hz, 2H), 7.33 (d, J = 8.4 Hz, 2H), 6.99 (d,
J = 9.2 Hz, 2H), 4.36 (t, J = 6.6 Hz, 2H), 4.05 (t, J = 6.6 Hz, 2H), 2.00 (s, 18H),
1.85–1.74 (m, 4H), 1.50–1.34 (m, 12H). MS (ESI) m/z: 635.0 [(M-{C6H4
COOC6H4C6H4CN})?Na]?. UV–Vis (CH2Cl2): kmax 349 (4318), 278 (46268),
229 (16888) nm.
Preparation of the Ruthenium Nanoparticles (7–10)
The L1-stabilized Ru nanoparticles 7 were prepared by reducing 1 (5 mg,
8.26 9 10-3 mmol) under solvent-free conditions in a magnetically stirred
stainless-steel autoclave (volume 100 mL) with H2 (50 bar) at 100 �C for 64 h.
Alternatively, the L1-stabilized Ru nanoparticles 8–10 were obtained by reacting
5 mg of [(arene)Ru(H2O)3]SO4 (for 8 arene = C6H6; for 9 arene = p-MeC6H4Pri;
for 10 arene = C6Me6) with one equivalent of ligand L1 in absolute ethanol (1 mL)
in a magnetically stirred stainless-steel autoclave (volume 100 mL) under 50 bar
pressure of H2 at 100 �C for 14 h. After pressure release, the solvent was removed
and the nanoparticles were dried in vacuo. The characterization of the nanoparticles
4
7–10 is presented in Figs. 1, 2, 3, and 4. The size distribution of the ruthenium(0)
nanoparticles was studied by transmission electron microscopy (TEM) using the
‘‘ImageJ’’ software [18] for image processing and analysis. The mean particle size
was estimated from image analysis of ca. 100 particles at least.
Cytotoxicity test (MTT assay)
Cytotoxicity was determined using the MTT assay (MTT=3-(4,5-dimethyl-2-
thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide. Cells were seeded in 96-well
plates as monolayers with 100 ll of cell solution (approximately 20,000 cells) per
well and preincubated for 24 h in medium supplemented with 10% FCS.
Compounds were added as DMSO solutions and serially diluted to the appropriate
concentration (to give a final DMSO concentration of 0.5%). The concentration
of the nanoparticle solutions used in the cytotoxicity assays is based on the
concentration of ruthenium in the precursor present in the solution used to prepare
the nanoparticles and assuming quantitative conversion. 100 ll of drug solution was
added to each well and the plates were incubated for another 72 h. Subsequently,
MTT (5 mg/mL solution in phosphate buffered saline) was added to the cells and
the plates were incubated for a further 2 h. The culture medium was aspirated, and
the purple formazan crystals formed by the mitochondrial dehydrogenase activity of
vital cells were dissolved in DMSO. The optical density, directly proportional to the
number of surviving cells, was quantified at 540 nm using a multiwell plate reader
and the fraction of surviving cells was calculated from the absorbance of untreated
control cells. Evaluation is based on means from two independent experiments, each
comprising three microcultures per concentration level.
N C
O
O O
N C
O
OO C
O
O
CN
RuCl Cl
Cl
arene
(1 - 6)
L1
L2
arene
L
C6H6 p-MeC6H4Pri C6Me6
L1 1 2 3
L2 4 5 6
Scheme 1 Synthesis of complexes [(arene)Ru(L)Cl2] (1–6)
5
Results and Discussion
The dinuclear complexes [(C6H6)RuCl2]2, [(p-MeC6H4Pri)RuCl2]2 and [(C6Me6)-
RuCl2]2 react in dichloromethane with two equivalents of the isonicotinic ester L1
or L2 to give the neutral complexes [(arene)Ru(L)Cl2] (1–6) in quantitative yield,
see Scheme 1. All the complexes are obtained as air-stable yellow to yellow/brown
powders, which are soluble in polar organic solvents, in particular in dichloro-
methane and in chloroform. The complexes are also sparingly soluble in water.
areneð ÞRuCl2½ �2þL! 2 areneð ÞRu Lð ÞCl2½ �The solventless reduction of solid [(C6H6)Ru(L1)] (1) with H2 (50 bar, 50 �C)
gives ruthenium nanoparticles 7 stabilized by the isonicotinic ester ligand L1, which
have a mean particle size of 8.5 nm (established by TEM). The size distribution of
these nanoscopic ruthenium particles (2–16 nm) is relatively large.
Smaller ruthenium nanoparticles stabilized by the isonicotinic ester ligand L1
were obtained by reducing [(arene)Ru(H2O)3]SO4 in ethanol at 100 �C with
molecular hydrogen (50 bar) in the presence of L1 (1 equivalent): The ruthenium
nanoparticles 8 obtained from [(C6H6)Ru(H2O)3]SO4 have a mean particle size of
2.8 nm, the Ru nanoparticles 9 obtained from [(p-MeC6H4Pri)Ru(H2O)3]SO4 have a
mean particle size of 2.3 nm, and the Ru nanoparticles 10 obtained from
0 2 4 6 8 10 12 14 16 18
Size of Particle [nm]
0
10
20
30
40
Dis
trib
utio
n [%
]
Size DistributionGaussian Fit
(c)
(b)(a)
Fig. 1 TEM micrograph (a) histogram (b) and EDS analysis (c) of ruthenium nanoparticles 7
6
[(C6Me6)Ru(H2O)3]SO4 have a mean particle size of 2.2 nm. The 1H NMR spectra
of 8–10 in CDCl3 show the presence of the ligand L1, the signals of the pyridine ring
being weak.
The in vitro cytotoxicity of 1–10 has been studied in the A2780 ovarian cancer
cell line and cisplatin resistant variant A2780cisR using the MTT assay.
Nanoparticles are finding increasing application in medicinal chemistry being used
as drug delivery agents, photodynamic therapy, luminescent imaging agents and
magnetic imaging agents. In particular, the selective accumulation of nanoparticles
in tumour tissue through the enhanced permeability and retention effect, and tunable
physical and chemical properties, are attractive properties for such applications
[19–22]. The ‘‘enhanced permeability and retention’’ (EPR) effect is a phenomenon
in which macromolecules are able to accumulate at the tumour site due to the
dramatic increase in blood vessel permeability within diseased tissues compared to
normal tissues [23]. To the best of our knowledge, these are the first examples of
ruthenium nanoparticles to be evaluated as potential antitumour agents. It should be
noted, however, that ruthenium based lipovectors that assemble to form lamellar
vesicles have recently been reported [24]. It should be noted that while most attention
has been focused towards mononuclear arene ruthenium anticancer compounds [2, 3,
25], there has been increasing interest in polynuclear complexes [26–29], including
clusters [30], which display excellent pharmacological properties.
1.2 1.6 2 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2
Size of Particle [nm]
0
10
20
30
Dis
trib
utio
n [%
]
Size DistributionGaussian Fit
(a) (b)
(c)
Fig. 2 TEM micrograph (a) histogram (b) and EDS analysis (c) of ruthenium nanoparticles 8
7
(c)
(b)
Size of Particle [nm]
0
10
20
30
40
50
Dis
trib
utio
n [%
]
Size DistributionGaussian Fit
(a)
0.4 0.8 1.2 1.6 2 2.4 2.8 3.2 3.6 4
Fig. 4 TEM micrograph (a) histogram (b) and EDS analysis (c) of ruthenium nanoparticles 10
1.2 1.6 2 2.4 2.8 3.2 3.6 4
Size of Particle [nm]
0
10
20
30
40
50
Dis
trib
utio
n [%
]
Size DistributionGaussian Fit
(b)(a)
(c)
Fig. 3 TEM micrograph (a) histogram (b) and EDS analysis (c) of ruthenium nanoparticles 9
8
The monomeric dichloro complexes of ligand L1 (1–3), exhibit very high
cytotoxicity in both the A2780 and resistant cell line, see Tables 1 and 2. In
particular, the benzene and p-cymene complexes have IC50 values equivalent to
cisplatin in the A2780 line (1.6 lM) and 2–3 fold lower in the cisplatin resistant line
A2780cisR [31]. Interestingly, the analogous pyridine complex [(p-MeC6H4Pri)-
Ru(py)Cl2] is essentially inactive (IC50 = 750 lM) under comparable conditions
[32], suggesting that the cytotoxicity of 1–3 may be due to the long-chain
isonicotinic ester group. This is supported by the very low IC50 values observed for
the free ligand L1 (5, 11 lM). In contrast, L2 exhibited much lower cytotoxicity, as
did complexes 4–6, possibly due to their poorer aqueous solubility.
The L1-stabilized Ru nanoparticles 7–10, also exhibit moderate cytotoxicity in
the ovarian cancer cell line, with the exception of p-cymene derived system 9,
which was unusually inactive (Table 3). For the other compounds, the size of the
nanoparticles and nature of the ligands in the precursor complex appears to have
little effect on cytotoxicity, with all three compounds exhibiting similar IC50 values
(29–39 lM). It seems probable that the isonicotinic ester ligand L1 is important to
the in vitro activity of the complexes given that the free ligand is so cytotoxic. In
fact, a number of structurally similar isonicotinic esters with long alkyl chains have
previously been reported to show interesting biological activity [33–35].
Table 1 Cytotoxicity of complexes 1–6 towards human ovarian cancer cells
compound A2780IC50 [µM]
A2780cisRIC50 [µM]
1 3 10
2 2 7
3 29 28
4 36 264
5 38 253
6 38 278
9
Conclusions
A series of arene ruthenium complexes containing a long-chain N-ligands were
prepared as were a series of ruthenium-based nanoparticles coated with the same
Table 2 Cytotoxicity of ligands L and arene ruthenium triaqua complexes towards human ovarian cancer
cells
Compound A2780IC50 [µM]
A2780cisRIC50 [µM]
L1 5 11
L2 225 303
[(C6H6)Ru(H2O)3]SO4 - 002>
[(p-MeC6H4Pri)Ru(H2O)3] SO4 >200 -
[(C6Me6)Ru(H2O)3] SO4 74 -
Table 3 Cytotoxicity of nanoparticles 7–10 towards human ovarian cancer cells
Ru nanoparticles mean size [nm]
A2780IC50 [µM]
7 8.5 29
8 2.8 34
9 2.3 >200
10 2.2 39
10
long-chain ligands. The cytotoxicity of the two series of compounds, i.e. small
molecule molecular complexes and nanoparticles, were evaluated in human ovarian
cancer cells (A2780). It was found that the small molecules were more cytotoxic
than the nanoparticles and while it is difficult to give a reason for this difference it
could be due to more efficient uptake of the mononuclear complexes. It is worth
noting that for the complexes, the cytotoxicities reflect, to some extent, that of the
free ligands. The cytotoxicity of the mononuclear complexes was also established in
the cisplatin resistant variant cell line, A2780cisR, and essentially the same degree
of resistance was observed for these compounds compared to that of cisplatin.
Overall, the similarity in cytotoxicites in the two studied cell lines between 1 and 2and cisplatin is remarkable, especially for such structurally different compounds.
However, it is too early to say whether these ruthenium compounds exert their
cytotoxic effect via a similar mechanism to cisplatin or whether different
mechanisms are in operation. While the ruthenium nanoparticles are less cytotoxic
than the complexes, the fact that they can potentially target tumour tissue selectively
via the enhanced permeability and retention effect, still endows them with promise,
but an in vivo study is needed to establish whether such systems really can
accumulate selectively in tumours.
Acknowledgments Financial support of this work from the Fonds National Suisse de la Recherche
Scientifique (Grant no. 200021-115821) is gratefully acknowledged. We also thank the Johnson Matthey
Research Centre for a generous loan of ruthenium(III) chloride hydrate.
References
1. G. Suss-Fink (2010). Dalton Trans. 39, 1673.
2. P. J. Dyson (2007). Chimia. 61, 698.
3. S. J. Dougan and P. J. Sadler (2007). Chimia. 61, 704.
4. L. D. Dale, J. H. Tocher, T. M. Dyson, D. I. Edwards, and D. A. Tocher (1992). Anti-Cancer DrugDesign. 7, 3.
5. C. S. Allardyce, P. J. Dyson, D. J. Ellis, and S. L. Heath (2001). Chem. Commun. 1396.
6. R. E. Morris, R. E. Aird, P. d. S. Murdoch, H. Chen, J. Cummings, N. D. Hughes, S. Pearsons,
A. Parkin, G. Boyd, D. I. Jodrell, and P. J. Sadler (2001). J. Med. Chem. 44, 3616.
7. G. V. Tsarichenko, V. I. Bobrov, and M. V. Smarkov (1977). Pharm. Chem. J. 11, 481.
8. J. Suarez, K. Ranguelova, and A. A. Jarzecki (2009). J. Biol. Chem. 284, 7017.
9. J. G. Małecki, R. Kruszynski, M. Jaworska, P. Lodowski, and Z. Mazurak (2008). J. Organomet.Chem. 693, 1096.
10. T. Arthur and T. A. Stephenson (1981). J. Organomet. Chem. 208, 369.
11. M. A. Bennett, G. B. Robertson, and A. K. Smith (1972). J. Organomet. Chem. 43, C41.
12. M. A. Bennett, T. W. Matheson, G. B. Robertson, A. K. Smith, and P. A. Tucker (1980). Inorg.Chem. 10, 1014.
13. M. S. Rothlisberger, W. Hummel, P.-A. Pittet, H.-B. Burgi, A. Ludi, and A. E. Merbach (1988).
Inorg. Chem. 27, 1358.
14. W. Weber and P. C. Ford (1986). Inorg. Chem. 25, 1088.
15. S. Ogo, T. Abura, and Y. Watanabe (2002). Organometallics. 21, 2964.
16. M. Marcos, M. B. Ros, J. L. Serrano, M. A. Esteruelas, E. Sola, L. A. Oro, and J. Barbera (1990).
Chem. Mater. 2, 748.
17. B. Dardel, D. Guillon, B. Heinrich, and R. Deschenaux (2001). J. Mater. Chem. 11, 2814.
18. M. D. Abramoff, P. J. Magelhaes, and S. J. Ram (2004). Biophotonics Int. 11, 36.
19. Y. Malam, M. Loizidou, and A. M. Seifalian (2009). Trends Pharm. Sci. 30, 592.
11
20. P. P. Jumade, A. M. Gupta, P. W. Dhore, P. S. Wake, V. V. Pande, and A. Deshmukh (2009).
J. Chem. Pharm. Sci. 2, 158.
21. M. E. Gindy and R. K. Prud’homme (2009). Exp. Opin. Drug Deliv. 6, 865.
22. W. Lin, T. Hyeon, G. M. Lanza, M. Zhang, and T. J. Meade (2009). MRS Bull. 34, 441.
23. D. F. Baban and L. W. Seymour (1998). Adv. Drug Deliv. Rev. 34, 109.
24. M. Vaccaro, R. Del Litto, G. Mangiapia, A. M. Carnerup, G. D’Errico, F. Ruffoa, and L. Paduano
(2009). Chem. Commun. 1404.
25. W. H. Ang and P. J. Dyson (2006). Eur. J. Inorg. Chem. 4003.
26. F. Schmitt, P. Govindaswamy, G. Suss-Fink, W. H. Ang, P. J. Dyson, L. Juillerat-Jeanneret, and
B. Therrien (2008). J. Med. Chem. 51, 1811.
27. P. Govender, N. C. Antonels, J. Mattsson, A. K. Renfrew, P. J. Dyson, J. R. Moss, B. Therrien, and
G. S. Smith (2009). J. Organomet. Chem. 694, 3470.
28. J. Mattsson, P. Govindaswamy, A. K. Renfrew, P. J. Dyson, P. Stepnicka, G. Suss-Fink, and Bruno.
Therrien (2009). Organometallics. 28, 4350.
29. M. G. Mendoza-Ferri, C. G. Hartinger, A. A. Nazarov, R. E. Eichinger, M. A. Jakupec, K. Severin,
and B. K. Keppler (2009). Organometallics. 28, 6260.
30. B. Therrien, W. H. Ang, F. Cherioux, L. Vieille-Petit, L. Juillerat-Jeanneret, G. Suss-Fink, and P. J. Dyson
(2007). J. Clust. Sci. 18, 741.
31. M. Auzias, B. Therrien, G. Suss-Fink, P. Stepnicka, W. H. Ang, and P. J. Dyson (2008). Inorg. Chem.47, 578.
32. C. A. Vock, C. Scolaro, A. D. Phillips, R. Scopelliti, G. Sava, and P. J. Dyson (2006). J. Med. Chem.49, 5552.
33. K. Furuta, H. Shirahashi, H. Yamashita, K. Ashibe, and E. Kuwano (2006). Biosci. Biotechnol.Biochem. 70, 746.
34. W. G. Friebe, W. Kampe, M. Linssen, and O. H. Wilhelms (1992). Ger. Offen. DE 4038335 A1
19920604.
35. D. S. Goldfarb (2009) U.S. Patent Appl. Publ. US 2009163545 A1 20090625.
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